玉龙雪山白水1号冰川退缩迹地的植被演替

Vegetation succession on Baishui No.1 glacier foreland,Mt.Yulong

运用空间代替时间,野外调查和因子分析的方法,研究了自小冰期最盛时以来的玉龙雪山白水1号冰川裸地的植被演替各个阶段的植物群落组成及其数量特征,演替过程中植被类型的变化及其解释,小冰期冰碛垄年龄的估测这3个主要内容。累计调查的55个样方中共出现91种植物,已鉴定出63个种,分属于28个科,46个属,双子叶植物居多,包括乔木、灌木和草本3种生活型的植物。通过统计分析各个演替阶段植物群落的数量特征,揭示出各个阶段植物群落的组成及其替代规律,即:在白水1号冰川末端近250a的退缩迹地上经历了裸地-草本-灌木-乔木的发展阶段。从生态位理论方面来看,这是由于不同物种的生态位及适应性都是不同的,所以构成了不同演替阶段的各自迥异的植物群落,优势种往往是那些生态位比较宽、适应性较强,能在多个演替阶段出现的物种。演替就是朝着生态位不断分化,能够最大限度利用资源的方向发展,其中物种的替代过程实质上就是在生态位不断的分化与接近,激烈的种内与种间竞争的过程中进行着的。基于此通过综合分析海螺沟与玉龙雪山的地理区位特征,气候状况,植被演替过程以及玉龙雪山地区相关的树轮方面的资料,来尝试着估测白水1号冰川小冰期终碛垄的年龄大约在170—250a之间。

A chronosequence study （ substituting space for time） was conducted following the retreat of alpine glaciers since the Little Ice Age. The study area is Baishui No. 1 Glacier, Mt. Yulong in Lijiang City, Yunnan Province of China. It is the biggest glacier on Yulong Snow Mountain. It has an area of 1.32 km^2 , the altitude of the equilibrium line is around 4850 m. After the greater advancement of Baishui No. 1 Glacier in Little Ice Age, the glacier had began to retreat, and form a large newly-exposed area. This area was divided into five successional seres： SUC1≈0-9 years; SUC2≈5-14 years; SUC5 ≈ 200-400 years. They were bounded by dated moraines deposited in 2002, 1997, and 17th and 19th centuries, but the age of the two seres （ SUC3 and SUC4） is unknow, they were located at an elevation of 4000 m and 3900 m. Then a successional sequence is formed by SUC1 to SUC5. Only a single site was chosen to represent each successional sere. At each sere ten 0.25 m^2 quadrats were chosen, we recorded percent cover, height and abundance of each herbaceous species. In SUC4 and SUC5, three 16 m^2 and two 100 m^2 quadrats were chosen to record height and abundance of bushes and trees respectively. By employing field investigation, factor analysis methods, this study mainly focuses on the communities composition and its number characteristics within different successional times, as well as the variations of vegetation types and the estimation to the age of the terminal moraine in the Little Ice Age. Among the investigated 55 plots, there are 91 types of plants, and about 63 species have been identified from it yet. They belong to 28 families and 46 genera, including arbor,shrub and herb three life forms plants, and most of species are dicotyledon, The number characteristics analysis for different succession stages reveals the communities composition and substitution regulation. Community composition is as follows： In the first successional sere, there are Cerastium caespitosum, Meconopsis horridula and Juncus brachystigma three communities, the dominant species is Cerastium caespitosum ; In SUC2, two communities are Polygonum macrophyllum and Carex capilllformis, the former is the dominant; Cerastium caespitosum, Carex capiUiformis, Carex crebra and Pedicularis sp. are the main communities in SUC3, and the dominant species is Cerastium caespitosum; Three communities are formed by Carex capilliformis, Carex crebra and Delphinium sp. , and the first one is the dominant in SUC4; Carex crebra, Ligustlcum rechingerana and carex kansuensis are the primary communities in the last successional sere. Carex crebra is the orientations of continuing differentiation of ecological niches, and each species try to take advantage of various resources. The species substitution processes often occur under the conditions of intense intraspecies and interspecies crossing competitions. In addition, based on the comprehensively analyses to the geographical characteristics, meteorological features of Mt. Gongga and Mt. Yulong, as well as the vegetation succession process, combing tree-ring materials of Mt.Yulong region, we estimated that the age of terminal moraine is about 170-250 years.